Originally Posted by NoaDon12
So in order to give more hiding places for the fish, i should add more plants. Right?
Plants do provide security for many fish, but assuming this is following along the lines of protecting fish from the aggression of tiger barbs, it is not the answer. I think enough members have commented on what you may be in for with these fish in a relatively confined space. And there is a psycological issue for the other fish.
In any aquarium fish have no escape from other fish, they are together within a relatively small volume of water permanently. In nature, fish can usually find refuge that keeps them out of sight of the aggressor. In an aquarium, the aggressor realizes that the other fish is still there (there are chemical indications as well as visual) and will be even more relentless than in the wild. The other fish become more and more stressed, and stress cause innumerable health problems.
Here's an example from my own experience. I put a group of Aphyocharax paraguayensis in a former 90g tank. I know that these fish, in spite of being quite small (3.5 cm or 1.4 inches), are boistrous and sometimes can be a bit nippy although most say less so than tiger barbs, but I figured that in a group of nine and in a 90g tank they would be fine. I was wrong. Within 2 days I noticed that almost all the other 70+ fish, which included largish tetras and Corydoras, were not swimming around as they had for months; at feeding time I saw why. The fish were cowering, literally, among the plants, and when the odd one did venture out to eat, one of the A. paraguayensis chased it. I did not observe any actual nipping, just chasing, but clearly something had to be done. I pulled the A. paraguayensis out, and after 2-3 hours the other fish sensed the danger was gone and began to come out one by one; next day they were fine, except for a bout of ich on several brought on by the stress.
The point is that fish are the way they are by nature, and while certain conditions in an aquarium can sometimes lessen the bad traits, it is not a certainty and sometimes the aquarium makes them worse. Small tanks almost always do this, probably another chemical issue as well as mere space. If you really want tiger barbs, and I admit they are a beautiful little fish, consider only a group of them in a suitably-sized tank. But I would not recommend them as community fish in anything other than larger aquaria, and then with reservations.